Technical Field
The invention relates a memory management method, and more particularly, relates to a read voltage level estimating method, a memory storage device and a memory control circuit unit.
Description of Related Art
The markets of digital cameras, cellular phones, and MP3 players have expanded rapidly in recent years, resulting in escalated demand for storage media by consumers. The characteristics of data non-volatility, low power consumption, and compact size make a rewritable non-volatile memory module (e.g., flash memory) ideal to be built in the portable multi-media devices as cited above.
Generally, in order to ensure a correctness of specific data, the data is encoded before writing it into the rewritable non-volatile memory module. The encoded data is then written into the rewritable non-volatile memory module. If that data is to be read, the encoded data is read and decoded. If the data can be successfully decoded, it means that there is only a small number of error bits, and those error bits can be corrected. However, if the data cannot be successfully decoded (i.e., the decoding fails), a different read voltage may be used to re-read the data. Nonetheless, under certain circumstances, the read data can still not be successfully decoded even if all the available read voltages have been used, resulting in a data read failure. Particularly, this data read failure becomes worse in the case where a block code is used for encoding.
Nothing herein should be construed as an admission of knowledge in the prior art of any portion of the present invention. Furthermore, citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention, or that any reference forms a part of the common general knowledge in the art.